Shark Cartilage has long been an alternative cancer treatment – very typical in that it has a shaky but superficially compelling theoretical basis, not empirical support, but plenty of anecdotes to lure the desperate. Promoters claim that sharks do not get cancer, because of anti-cancer properties of their cartilage. However – sharks do get cancer.

Proponents further claim that shark cartilage (and other cartilage products, like bovine cartilage) increase immune activity, kill cancer cells, and prevent angiogenesis – the formation of new blood vessels to feed tumors. None of these properties have been demonstrated, however.The anti-angiogenesis theory is at least plausible – but the simple fact is, if this potential were there a pharmaceutical company would have isolated, purified, and produced a drug based upon the cartilage long ago – with proven efficacy. There has been some interesting basic science, but nothing that has led to an effective drug. And what is on the market is mostly “crude extracts” – nothing but snake oil.

Despite years of use, and millions of dollars spent by cancer patients on dubious cartilage products, the evidence has been solidly negative. So negative, in fact, that we can confidently conclude that shark cartilage is probably not an effective treatment for any type of cancer. There is certainly no justification for its use, which has led to several very negative outcomes: a decline in shark populations, worse outcomes for cancer patients who delayed or ignored proven treatments due to the false promises of shark cartilage, and a vast waste of resources, mostly diverted to people of dubious credibility and motivations.

If we lived in a more rational world, that would be the end of it – but we don’t. So we need to waste money doing further research, going way beyond due diligence, just to serve the irrational beliefs of a subset of the public. That is, in fact, largely what the National Center for Complementary and Alternative Medicine does, which is why they funded (along with the National Cancer Institute) a study of shark cartilage in non-small cell lung cancer.

The study was a double-blind placebo controlled trial with 379 subjects of standard therapy + placebo vs standard therapy + AE-941 (a brand of shark cartilage). You can read the details in the linked abstract – suffice it to say the results were dead negative. There was no benefit.

Sure – this is just one study of one type of cancer. Cancer is a category of disease, not one disease. I am not saying this should be sufficient to abandon any particular treatment. However, this is just the latest in a long line of negative studies of shark cartilage. When is enough enough?

Even if there are researchers who want to explore this further, that is fine. But there is certainly no justification for a market for shark cartilage for cancer. If anything meets the definition of snake oil, this does. I think we can also conclude that any country that claims to have effective regulation of health products that protects their citizens from worthless or harmful products or false claims, should not allow the sale of shark cartilage for cancer. In other words – we do not have effective regulation of health products. Some people believe that we do not need such regulation, which is a political/ideological opinion they are welcome to. But I think we can objectively say – we don’t have it.

I am glad to have this new evidence to combat the true-believers and snake-oil promoters. But scientific evidence needs to be coupled, in my opinion, with effective regulation, otherwise we are just talking to ourselves.

“So we need to waste money doing further research, going way beyond due diligence, just to serve the irrational beliefs of a subset of the public. ”

I feel the need to emphasise this issue whenever it comes up: lets stop doing research in unpromising areas just because some people have irrational beliefs about them. Unless there is scientific plausibility and unanswered questions we should abandon this approach because its a waste of resources. It is very inefficient to attempt to sway people’s beliefs with evidence when evidence was never the basis of those beliefs.

The main positive effect of doing this type of research is of getting the story to the news, but like I said that is ineffcient and bottom-line doesnt work. Think about it this way… if more research and information were the solution then the research that has come from the NCAAM would have resulted in a huge drops in vitamin/ supplement sales over the past 2 decades. Of course that hasn’t happened… not even close… the trend has been a pretty steady increase.

When there is no evidence deficiency, evidence is not a good treatment

Well, to be fair concerning NCCAM, the negative results haven’t exactly been headline news. (Even though it really should be.) So the information hasn’t even really been distributed to the people who might change their minds, even though most would dismiss.

I’m not generally as critical of traditional media as some are, but not taking up stories like shark cartilage and NCCAM results definitely been a serious error on their part.

I agree it is a waste of money and won’t fix anything. However I would like to see NCAAM have a definitive trial and attempt to be an actual authority on alternative medicine. I know that after enough negative trials it will be run down by all Alternative Medicine Advocates as part of the conspiracy. For those that do not buy into this it could be another great resource.

Much like Dr. Novella wrote about yesterday, people trust their friends and groups more than data. So if someone at your gym or someone who did recover from cancer tells you of something you should be doing to improve yourself, people will do it and, most of the time, never look at the evidence. I think getting the headlines is invaluable to keeping some skepticism in popular culture. I just feel like it should take hundreds of thousands of dollars a pop to do. Every time there is a new craze, the media should be saying, here’s what’s happening, here’s the evidence and what it says. Of course they do not (currently what I’m nerd raging over).

-Well thats the point. It does make the news on occasion, but people aren’t interested in the “negative” studies… if they were then it would make more headlines. Plus its harder to sensationalize these studies. I’m not sure who you are being ‘fair’ to in that statement. All parties involved are at fault to a great degree.

“However I would like to see NCAAM have a definitive trial and attempt to be an actual authority …”

Its a tough thing to be in charge of something with the end result may be putting yourself ‘out of business.’ How can we really expect the level of perspective and objectivity with this in mind?

“people trust their friends and groups more than data.”

That is true for many, but even the people you know get information from somewhere, such as news outlets and talk shows.

Thanks for this blog! The animal protection community (of which I am a member) as a whole is woo susceptible. I try to point out how science is our friend and cite examples like shark cartilage. Science really is the answer to many problems. I will refer people to this blog and this site.

Yes, I second the frustration about continuing research in unpromising areas. In basic science research, no matter how enthusiastically you cling to a given pet theory, if it has low prior probability coupled with consistently negative empirical results, there is no way in hell you’re getting any further investigation of it funded. There should absolutely not be a special case exception in clinical research for any claim that involves irrational albeit popular beliefs. Wasting public funds researching clearly bogus CAM claims is a subjugation of science by irrational thinking and should offend anyone with an appreciation for science.

This would not be a huge issue if we lived in an economy with a surplus of research funds, but right now given the NIH funding threshold in most fields, you have to imagine that boatloads of promising proposals are sitting on the NIH’s desk unfunded while we do yet another study that tells us that “yup, shark cartilage is just pseudoscientific wishful thinking.”

It’s irrelevant anyway, the reason sharks don’t develop cancer very often is because they get regular exercise and don’t eat processed food, and they can’t smoke underwater.

The reason sharks don’t develop cancer very often is because they have (on average) low metabolisms and low growth rates, and don’t turn over their cells as often as us mammals. Fewer cell divisions means fewer chances for somatic mutations during mitosis means less chance of activating an oncogene.

I’m new to the blog, and am loving it.
I have to offer an objective warning though- and that is that a great deal of energy seems to be spent ranting about how the general population is so darned ignorant.

It’s true. We know it. And I think even more people than you’d guess even know that they aren’t educated. Bad syntax on that one, but I think you know what I mean.

Anyway, the real question is this: What good does it do to expound on your frustrations and complaints.

There’s limited energy in the universe, right? So why not put some of those limited resources into positive solutions?

Just a little warning,
No one wants to look like the angry egghead grumbling in a box.

‘Wasting public funds researching clearly bogus CAM claims is a subjugation of science by irrational thinking and should offend anyone with an appreciation for science.’

This is an important point, concisely written. People often overlook the problem because it is in some ways a subtle subjugation.

“Anyway, the real question is this: What good does it do to expound on your frustrations and complaints. There’s limited energy in the universe, right? So why not put some of those limited resources into positive solutions?”

Listen, I hear you and I agree with the perspective… but you have to consider the venue here. What good does it do? Sometimes engaging in conversation about such topics help with insight into the mechanisms of these problems of critical thinking. Its not just ‘people are stupid, blah, blah, blah’ but the who, what, where, when, why and how. Sometimes if we can obtain some insight, it is easier to help ourselves and others. And who says that positive solutions don’t come from people who also complain. Its not an either/or situation.

Angry egghead in a box is a problem that I’ve seen, but I think frustrated is more common. I think most people are not that dismissive of others as much as they may write in the comments of a blog.

Positive comments are less likely when we are talking about selling false hope to cancer victims

“a great deal of energy seems to be spent ranting about how the general population is so darned ignorant. ”

I don’t think it is productive to rant against the general population of science illiterate people. I used to be science illiterate myself. But it is painful to see some scientifically educated people around here rant on about their pet theories seemingly oblivious to the very unscientific attitude they take towards them.

They seem to know the scientific facts, but do not seem to be conversant with scientific methodology itself, and they extrapolate wildly beyond the empirically derived facts in support of their pet theories.

They seem to be unable to distinguish between the practical assumptions of science by which science moves forward and their own pre-conceived endpoints into which they conscript science. Science, in this sense, is the master, not the servant.

My impatience for unscientific alternative medicine was triggered by a friend, or an acquaintance who became a friend, who suffered, not from lung cancer, but from colon cancer and who was conscripted into the cause of alternative medicine by a well meaning but ignorant friend who convinced him that shark cartilege could save his life.

He’d had all the conventional medical treatments, including surgery and chemotherapy, but unfortunately went on to develop incurable disease. So, at the age of 28, he faced an illness which was to prove fatal within about 6 months. He and his wife had decided to use the time that remained to fulfill a dream they always had of travelling around Australia by car. They cashed in part of his life insurance and were about to set off when the so called “miracle cure” was dropped into his lap.

What to do? They pondered the question for several days. But eventually they decided that he just had to give it a go. The travel plans were put on hold and off he went to the “miracle worker”. The “miracle worker” in this case happened to be a medical practitioner with an interest in alternative medicine, which sort of lent some legitimacy to the treatment.

For five months he had weekly shark cartilege injections given by this doctor. Of course the treatments had no effect whatsoever. The scans showed the cancer was progressing. But the real revelation occured when he did some investigation about the treatment he was being given and discovered that, over and above his consultation fee, this doctor was marking up the price of the actual injection by over 200%!

Unfortunately, he lost five months to this self-serving quack and his self-serving quackery, so that when he and his wife finally set off on their trip, he was already beginning to suffer from some of the early symptoms of preogressive disease. Within a few weeks he had developed incessant vomiting and extreme fatigue and had to be flown home. Within a few days he was admitted into hospital for terminal care and he died a few weeks later.

This even had to be investigated ?
What possible mechanism would be at work here ?
Shark Cartilage … cancer… Sorry, just not seeing it.
I remember the whole “shark cartilage for arthritis” thing, and if I remember right there was another “shark cartilage as antioxidant” thing. And none of it ever showed more than placebo effect in properly run trials.

Yes, science is becoming more and more specialized beyond what the average person can truly understand, but thats where critical thinking comes into play. Combined with a general scientific literacy, it allows people to make reasonable judgements about things they may not completely understand by using some basic principles that apply to many topics.

The reason sharks don’t develop cancer very often is because they have (on average) low metabolisms and low growth rates, and don’t turn over their cells as often as us mammals.

That makes sense. I had always suspected that a paucity of data (most sharks are pelagic, after all, which makes them harder to study) was the real reason we didn’t see much cancer in sharks, but that explanation makes more sense.

I never understood why some people attributed it to their cartilage. It just seems kind of random. Why not their meat? Or their gills? Organs? Fins? (That one would go well with the claim that Asian people don’t get as much cancer — shark fin soup, after all.) Obviously, they didn’t understand why sharks weren’t getting cancer; so why pick on the cartilage? There must have been some reason, but I’m not familiar with the history of shark cartilage for cancer.